This is a renewal application for a Program Project Grant or the theme of diet and cancer epidemiology. This theme is pursued with studies that explore etiologic hypotheses as well as methodologic aspects of dietary assessment. In the current period of support, a population-based prospective cohort of 42,000 subjects is being followed for cancer incidence in relation to antecedent dietary intakes; case-control studies are testing dietary hypotheses related to lung, bladder and thyroid cancers; and the quantitative diet history method is being evaluated for accuracy of recall, as well as for differences in recall between cases versus controls and between proxy respondents versus directly-interviewed subjects. Substantial progress is being made on all of these projects and preliminary findings are presented. In the renewal period, six projects are proposed: 1) continued surveillance for cancer incidence in the prospective cohort; 2) a case-control study (1057 cases, 1057 controls) of the relationship of dietary fat, fiber and calcium intake, as well as energy balance, to colorectal cancer risk; 3) a case-control study (391 cases, 782 controls) of the possible association of dietary fat and vitamin A with endometrial cancer risk; 4) a correlational study of dietary factors and cancer incidence in Filipino, Caucasian and Japanese migrants to Hawaii; 5) a case-control study (231 cases, 462 controls) of dietary vitamins A, C and E and selenium in relation to risk of cutaneous malignant melanoma among Caucasians; 6) development of a telephone interview method for quantitative diet history assessment. The case-control studies will involve direct interviews of subjects in their homes, using a quantitative diet history method with visual aids. In addition, the study of malignant melanoma will include serum collections for assays of retinol, carotenes, alpha- tocopherol and selenium. Follow-up on the prospective cohort will entail computerized record-linkage with the Hawaii Tumor Registry and other vital records. The telephone interview study will include both face-to-face and telephone interviews with 300 subjects. Data collection, processing and analysis for these projects is highly integrated, and provides for synergism and economy in effort that would not otherwise be possible. The results of these studies should further our knowledge of the relationship of diet to cancer risk and strengthen the foundation for future public health efforts in the primary prevention of cancer.